I am also having this problem when I tried to play a midi file I was told by add remove applications to install amarok which I did, and it does not play midi files when I double click on them. media could not be played or some such, but in the program description it says it can, so one of the two is broken either the program or its description.
type: audio/midi into add remove applications...

Why then, having Amarok not yet installed, doubleclicking on a mid-file returns with msg, that an appropriate player is not available - so far so good - but proposes 2 players, one of them is Amarok, to install, if Anarok cannot play mid-files?

the problem is that ubuntu makes suggestions according to the application's configuration files, now amarok included midi (though it shouldn't have) ... it has been removed in due to release version 1.4.6 - which will appear in Gutsy